JP2906565B2 - Gear ratio control device for continuously variable transmission for vehicles - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed ratio control device for a continuously variable transmission for a vehicle.

2. Description of the Related Art A continuously variable transmission for a vehicle, which continuously changes the rotation of an engine and transmits it to drive wheels, is usually determined based on a required output value such as an accelerator pedal operation amount, a throttle valve opening, and a vehicle speed. The gear ratio is controlled so that the set target value is achieved. For example, the one described in JP-A-59-144850 is that.

Problems to be Solved by the Invention By the way, in the conventional gear ratio control device for a continuously variable transmission for a vehicle, there is a relationship having a characteristic that the target rotation speed increases as the throttle valve opening increases and as the vehicle speed increases. Since the engine is used, the engine cannot be operated in a high rotation range at a low vehicle speed. For this reason, a driving force cannot be obtained in a low vehicle speed / high required output region such as when the vehicle starts or when the vehicle is accelerating in a low-speed running state, so that there is a disadvantage that sufficient acceleration cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a continuously variable transmission for a vehicle capable of obtaining sufficient acceleration in a low vehicle speed and a high required output range. It is to provide a control device.

Means for Solving the Problems The gist of the present invention for achieving the object is to provide a continuously variable transmission for a vehicle in which the rotation of an engine is steplessly changed and transmitted to driving wheels. A speed ratio control device for adjusting a speed ratio of a transmission, comprising: (a) a required output sensor for detecting a required output value of the vehicle;
A vehicle speed sensor for detecting a speed of the vehicle; and (c) in a high load region in which the required output value of the vehicle is higher than a predetermined value, in a high vehicle speed region equal to or higher than a predetermined vehicle speed, the engine rotation speed of the vehicle is constant. In a low vehicle speed region below a predetermined vehicle speed, the target value is changed so as to increase the engine rotation speed of the vehicle as the vehicle speed is lower. In a low load region where the required output value of the vehicle is lower than the predetermined value, Storage means for storing in advance a relationship for maintaining a target value so that the engine rotation speed of the vehicle is constant; and (d) determining a target value based on the required output value and the vehicle speed of the vehicle from the previously stored relationship. And a gear ratio adjusting means for adjusting the gear ratio of the continuously variable transmission so as to determine the target value.

In this way, in the high vehicle speed region where the required output value of the vehicle is higher than the predetermined value in the high load region and the required output value of the vehicle is equal to or less than the predetermined value,
Since the target value is determined so that the engine rotation speed of the vehicle is constant, the engine is operated on an optimum curve in consideration of fuel efficiency and drivability, and the required output value of the vehicle is higher than a predetermined value. In a low vehicle speed region below a predetermined vehicle speed in the load region, the target value is determined based on the required output value of the vehicle and the vehicle speed because the target value is changed so that the lower the vehicle speed, the higher the engine rotation speed of the vehicle. In a low vehicle speed and high demand output region such as when the vehicle starts or accelerates in a low-speed running state, the high rotation region of the engine can be used, and the driving force and acceleration of the vehicle can be sufficiently obtained.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 2, the power of an engine 10 is controlled by a fluid coupling 12 with a lock-up clutch, a belt-type continuously variable transmission (hereinafter referred to as CV).
A drive wheel connected to a drive shaft 22 via a forward / reverse switching device 16, an intermediate gear device 18, and a differential gear device 20;
24.

The fluid coupling 12 includes a pump impeller 28 connected to the crankshaft 26 of the engine 10, a turbine impeller 32 fixed to the input shaft 30 of the CVT 14 and rotated by oil from the pump impeller 28, and a damper 34. A lock-up clutch 36 fixed to the input shaft 30 via an engagement portion, an engagement-side oil chamber 33 connected to an engagement-side oil passage 37, and a release-side oil chamber 35 connected to a release-side oil passage 39. I have. The inside of the fluid coupling 12 is always filled with hydraulic oil, and when the hydraulic oil is supplied to the engagement-side oil chamber 33 and the hydraulic oil flows out from the release-side oil chamber 35, the lock-up clutch 36 is engaged. Let the crankshaft 26
And the input shaft 30 are directly connected. Conversely, the release side oil chamber
When the hydraulic oil is supplied to 35 and the hydraulic oil flows out from the engagement side oil chamber 33, the lock-up clutch 36 is released.

The CVT 14 has a primary variable pulley 40 and a secondary variable pulley 42 provided on its input shaft 30 and output shaft 38, respectively.
And a transmission belt 44 wound around the variable pulleys 40 and 42. The variable pulleys 40 and 42 are fixed rotating bodies fixed to the input shaft 30 and the output shaft 38, respectively.
46 and 48, and movable rotators 50 and 52 provided on the input shaft 30 and the output shaft 38 so as to be movable in the axial direction and not to rotate relatively around the axis, respectively.
Is moved by the primary hydraulic cylinder 54 and the secondary hydraulic cylinder 56 that function as hydraulic actuators, thereby changing the V-groove width, that is, the hanging diameter (effective diameter) of the transmission belt 44, and changing the speed ratio γ (= The rotation speed N _in of the input shaft 30 / the rotation speed N _out of the output shaft 38) is changed.

The forward / reverse switching device 16 is a well-known double pinion type planetary gear mechanism, and includes a pair of planetary gears 62 and 64 rotatably supported by a carrier 60 fixed to an output shaft 58 thereof and meshing with each other. Planetary gear 6 fixed to the input shaft (output shaft of CVT 14) 38 of the
2, a sun gear 66 meshing with 2, a ring gear 68 meshing with the planetary gear 64 on the outer peripheral side, a reverse brake 70 for stopping rotation of the ring gear 68, the carrier 60 and the input shaft 38 of the forward / reverse switching device 16 are connected. And a forward clutch 72 to be driven. The reverse brake 70 and the forward clutch 72 are friction engagement devices of a type operated by hydraulic pressure.
Is set to a neutral state, and power transmission is interrupted. However, when the forward clutch 72 is engaged, the output shaft 38 of the CVT 14 is
And the output shaft 58 of the forward / reverse switching device 16 are directly connected to transmit power in the forward direction of the vehicle. When the reverse brake 70 is engaged, the output shaft 38 of the CVT 14 and the forward / reverse switching device 16
The rotation direction is reversed between the output shaft 58 and the output shaft 58, so that the power in the vehicle backward direction is transmitted.

A hydraulic pump 74 that is driven to rotate by the engine 10 is a hydraulic source of a hydraulic control circuit 76 shown in FIG. The hydraulic control circuit 76 is for controlling the vehicle power transmission device. For example, JP-A-62-196449, JP-A-64-49749, Japanese Patent Application No. 1-78784, Alternatively, the configuration is the same as that of the hydraulic control circuit described in Japanese Patent Application No. 1-333141. The hydraulic control circuit 76 includes a first solenoid valve 80 for controlling a shift direction control valve (not shown) and a second solenoid valve 82 for controlling a shift speed control valve (not shown). CV related to the ON / OFF operation state of the first solenoid valve 80
The change direction of the speed ratio γ of T14 is switched, and the second solenoid valve 8
Since the speed of change of the gear ratio γ is switched in relation to the on / off operation state of the second solenoid valve 2, the first solenoid valve 80 and the second solenoid valve 82
Depending on the combination of the operating states of, the rapid increase mode in which the gear ratio γ is quickly changed to the speed increasing side, the rapid deceleration mode in which the gear ratio γ is quickly changed to the reduced speed side, and the gear ratio γ is gradually changed to the increased speed side The slow acceleration mode and the slow deceleration mode for gradually changing the speed ratio γ to the deceleration side are respectively established, and between the rapid acceleration mode and the slow acceleration mode, and between the rapid deceleration mode and the slow deceleration mode. Target mode is 2nd
This is established by the duty drive of the solenoid valve 82.

Further, the hydraulic control circuit 76 is provided with a third solenoid valve 84 for controlling the engagement state of the lock-up clutch 36. When the third solenoid valve 84 satisfies predetermined conditions in consideration of fuel efficiency and drivability, for example, at least the vehicle speed v among the vehicle speed v, the input shaft rotation speed N _in , and the throttle valve opening _θth is predetermined. The lock-up clutch 36 is engaged by supplying hydraulic oil to the engagement-side oil chamber 33 and allowing the hydraulic oil to flow out of the release-side oil chamber 35 to engage the lock-up clutch 36 with the crankshaft 26. The input shaft 30 is directly connected. Conversely, when the vehicle speed v or the like becomes equal to or less than the predetermined value, the lock-up clutch 36 is released by supplying the hydraulic oil to the release-side oil chamber 35 and causing the hydraulic oil to flow out of the engagement-side oil chamber 33.

The electronic control unit 90 functions as the speed ratio adjusting means of the present embodiment, and by driving the first solenoid valve 80, the second solenoid valve 82, and the third solenoid valve 84 in the hydraulic control circuit 76. , And controls the gear ratio γ of the CVT 14 and the lock-up clutch 36. The electronic control unit 90 includes a CPU 92, a ROM 9
4, a so-called microcomputer comprising a RAM 96, an interface circuit (not shown), etc., which includes a vehicle speed sensor 102 for detecting the rotation speed of the drive wheels 24, and the rotation speed of the input shaft 30 and the output shaft 38 of the CVT 14 respectively. Input shaft rotation sensor 104 and output shaft rotation sensor 106, throttle valve opening sensor 108 for detecting the opening of a throttle valve provided in the intake pipe of engine 10, and operating position for detecting the operating position of shift lever 100. sensor 110, a brake switch 112 for detecting operation of a brake pedal, a signal representing the vehicle speed v, a signal indicative of an input shaft rotational speed N _in the signal representing the output shaft speed N _out, the throttle valve opening theta _th signals representing a signal representing an operation position P _s of the shift lever 100, a signal representative of a brake operation are supplied.
The throttle valve opening θ _th corresponds to the required output value of the vehicle, and the throttle valve opening sensor 108 functions as the required output sensor of the present embodiment. The CPU 92 in the electronic control unit 90 uses the temporary storage function of the RAM 96 while
An input signal is processed according to a program stored in advance in M94, and the first solenoid valve 80, the second solenoid valve 82, and the third solenoid valve 84 are processed.
And outputs signals for driving.

The electronic control unit 90 controls the gear ratio γ in accordance with a control routine stored in advance as shown in FIG. 3, for example. In FIG. 3, after initialization is performed in a step (not shown), input signals and the like from each sensor are read in step S1, and a vehicle speed (a so-called driving wheel vehicle speed) v is determined based on the read signals. , The rotation speed N _in of the input shaft 30 and the rotation speed N _out of the output shaft 38, and the speed ratio γ of the CVT 14 is calculated as necessary from these N _in and N _out . In the following step S2,
From the relationship shown in FIG. 1 stored in the predetermined storage area 114 of the ROM 94, the target input shaft rotation speed N _in ^* is calculated based on the actual throttle valve opening θ _th and the vehicle speed v. In this embodiment, the storage area 114 functions as a storage unit that stores the relationship shown in FIG. 1 in advance. The above relationship is based on, for example, the optimal curve taking into account the fuel efficiency and drivability.
Is basically obtained in advance in order to operate the motor.
N _in ^* is assumed to be constant. Further, in this relationship, as shown in region A of FIG. 1, the throttle valve opening theta _th e.g.
In the region where the required output value exceeds 80%, the engine speed Ne of the vehicle is kept constant in the high vehicle speed region.
In the low vehicle speed range, the lower the vehicle speed V, the more the engine speed of the vehicle
A characteristic of changing the target input shaft rotation speed N _in ^* so as to increase Ne is provided, and consideration is given to enhancing acceleration during starting operation or low-speed running.

Then, in step S3, with the difference between the actual rotational speed N _in the target input shaft rotational speed N _in of the input shaft 30 ^*, that is, the control deviation ^{_{ΔN in (= N in * -N}} in) is calculated, step In S4, a control mode for eliminating the control deviation ΔN _in is selected. That is, the deviation ΔN _in in the feedback control of the speed ratio γ becomes zero,
In other words, the shift mode and the duty ratio D _S2 are determined so that the target input shaft rotation speed N _in ^* and the actual input shaft rotation speed N _in (= engine rotation speed _Ne ) match.

When the shift mode or the duty ratio is determined in this way, in step S5, the first solenoid valve 80 and the second solenoid valve 82 are driven so as to obtain the shift mode or the duty ratio _DS2 . Then, the above steps by is repeatedly executed, the gear ratio so that the actual input shaft speed N _in is equal to the target input shaft speed N _in ^* gamma
Is adjusted.

Although than that speed ratio to match the actual input shaft speed N _in as described above to the target input shaft rotational speed N _in ^* is adjusted, in this embodiment, the target input shaft rotational speed N _in ^* Since the relationship shown in FIG. 1 is used for the determination, sufficient acceleration can be obtained at the time of starting operation of the vehicle or at the time of accelerating operation at low vehicle speed. That is, as shown in the region A of FIG. 1, in the region where the throttle valve opening θ _th is large,
The characteristic that the target input shaft rotation speed N _in ^* is changed so that the engine rotation speed Ne of the vehicle increases as the vehicle speed V decreases in the low vehicle speed region so that the engine rotation speed Ne of the vehicle is constant in the high vehicle speed region. In accordance with, the target input shaft rotation speed N _in ^* is determined, so that the high rotation region of the engine 10 can be used at a low vehicle speed and a high required output region such as at the time of start of the vehicle or at the time of acceleration in a low speed running state, The driving force and acceleration of the vehicle can be sufficiently obtained.

FIGS. 4 and 5 show the relationship used for determining the target input shaft rotation speed N _in ^* _in the conventional gear ratio control device. As shown in a region B of FIG. 4 and a region C of FIG. 5, in the high required output region, the target input shaft rotation speed N _in ^* becomes smaller or smaller than the high vehicle speed region as the vehicle speed becomes lower. Therefore, the rotation of the engine 10 could not be increased when the vehicle started or when the vehicle was accelerating at low vehicle speed, and it was difficult to obtain a sufficient driving force or acceleration force.

As mentioned above, although one Example of this invention was described based on drawing, this invention is applied also in another aspect.

For example, in the above-described embodiment, the target input shaft rotation speed N
_{Although the} gear ratio γ was controlled so that _in ^* and the actual input shaft rotation speed N _in coincided with each other, such feedback control is not necessarily required, and the target input shaft rotation speed described above is not necessarily required.
An open-loop control may be used in which a control amount for obtaining N _in ^* is determined according to a control formula stored in advance, and the speed ratio γ is adjusted according to the control amount.

Further, instead of the hydraulic control circuit 76 of the above-described embodiment, the line hydraulic pressure is always applied to the secondary hydraulic cylinder as described in Supplying hydraulic oil into the hydraulic cylinder on the side or discharging hydraulic oil from the hydraulic cylinder on the primary side
The vehicle may be of a type that controls the gear ratio of T.

Further, in the above-described embodiment, the feedback control of the gear ratio γ is performed by matching the actual input shaft rotation speed N _in with the target input shaft rotation speed N _in ^* , but γ ^* = N
because it is _in ^* / N _out, determines a target gear ratio to replace the target input shaft rotational speed N _in ^* γ ^*, adjusting the speed ratio gamma to match the target speed ratio gamma ^* the actual gear ratio gamma The control is substantially the same.

The above is merely an example of the present invention, and the present invention can be variously modified without departing from the gist thereof.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship stored in advance used in the flowchart of FIG. FIG. 2 is a block diagram showing a gear ratio control device according to one embodiment of the present invention. FIG. 3 is a flowchart for explaining the control operation of the embodiment of FIG. FIG. 4 and FIG. 5 are first and second relations used in a conventional gear ratio control device.
It is a figure equivalent to a figure. 14: CVT (belt-type continuously variable transmission) 90: electronic control unit (speed ratio adjusting means) 102: vehicle speed sensor 108: throttle valve opening sensor (required output sensor) 114: storage area (storage means)

Continuation of the front page (51) Int.Cl. ⁶ identification code FI F16H 63:06 (58) Investigated field (Int.Cl. ⁶ , DB name) F16H 59/00-61/12 F16H 61/16-61 / 24 F16H 63/40-63/48

Claims (1)

(57) [Claims] 1. A continuously variable transmission for a vehicle that continuously changes the speed of rotation of an engine and transmits it to driving wheels, wherein the speed ratio control device is configured to adjust a speed ratio of the continuously variable transmission. A required output sensor for detecting a required output value of the vehicle, a vehicle speed sensor for detecting a speed of the vehicle, and a high load region where the required output value of the vehicle is higher than a predetermined value. The target value is changed so that the engine rotation speed of the vehicle is constant, and in a low vehicle speed region equal to or lower than a predetermined vehicle speed, the lower the vehicle speed, the higher the engine rotation speed of the vehicle. In the following low load range, storage means for storing in advance a relationship for maintaining a target value so that the engine speed of the vehicle is constant regardless of the vehicle speed; and a required output of the vehicle from the previously stored relationship. Speed ratio adjusting means for determining a target value based on the vehicle speed and the vehicle speed, and adjusting a speed ratio of the continuously variable transmission so that the target value is realized. Gear ratio control device.